1. Field of the Invention
The present invention relates to a grasping forceps for an endoscope which is inserted into a channel formed in an endoscope for allowing a treating instrument to pass therethrough and used for grasping and picking out an object such as a foreign body, polypus and so on within a body cavity.
2. Disclosure of the Related Art
Recently, in addition to the medical examination of a body cavity by an endoscope, there has been known such an art that a grasping forceps for an endoscope such as an in vivo inspection forceps, a grasping forceps inserted into a treating instrument passing channel formed in the endoscope is inserted into the body cavity for grasping and recovering a foreign body within a living body or for grasping and picking out cellular tissue to be inspected.
The grasping forceps for the endoscope comprises a flexible insertion section composed of a coil sheath and the like externally covered with, for example a flexible resin tube, an operating wire passing through this insertion section, an operating section connected with the operating wire at its hand-side end, and a plurality of elastic grasping members arranged at the leading end of the operating wire and having a habit of flexing so as to spread outwards.
For example, as shown in FIG. 1(A), a conventional grasping forceps 10 for an endoscope has an elastic grasping section 14 composed of three elastic grasping members 11, 12, 13. These elastic grasping members 11, 12, 13 are connected to the leading end of the operating wire. When an operator moves the operating wire toward the leading end side by the manipulation of a finger-engaging member disposed at the hand-side end of the operating wire, the leading end portions of the elastic grasping members 11, 12, 13 are projected from a leading end surface 15a of an insertion section 15. Thereupon, the elastic grasping section 14 spreads outwards from the center axis of the insertion section 15 owing to the elastic restoring forces of the respective elastic grasping members 11, 12, 13.
Further, circular pawl portions 11a, 12a, 13a are formed at the leading end portions of the three elastic grasping members 11, 12, 13 so as to face inwards with respect to the advancing and retreating direction of the operating wire. In the Japanese Utility Model Laid Opened Publication No. 5-62214 disclosed is such a grasping forceps for an endoscope that leading end grasping portions bent nearly perpendicularly relative to a center axis of an insertion section of the grasping forceps for the endoscope are formed at leading ends of a plurality of elastic grasping members constructing an elastic grasping section.
In the grasping forceps 10 for the endoscope, when the finger engaging member is operationally pushed and pulled by the operator, the operating wire is advanced and retreated, so that the leading end portions of the elastic grasping members 11, 12, 13 are projected from and concealed in the leading end surface 15a of the insertion section 15. Thereby, the circular pawl portions 11a, 12a, 13a formed at the leading ends of the elastic grasping members 11, 12, 13 having the habit of flexing are opened and closed.
That is, when the operating wire is operationally pushed, the elastic grasping members 11, 12, 13 are projected from the leading end surface 15a of the insertion section 15, so that the circular pawl portions 11a, 12a, 13a formed at the leading ends of the respective elastic grasping members 11, 12, 13 spread outwards from the center axis of the insertion section 15 owing to the elastic restoring forces of the elastic grasping members 11, 12, 13.
On one hand, when the operating wire is operationally pulled, the elastic grasping members 11, 12, 13 are gradually pulled into the insertion section, so that the spread circular pawl portions 11a, 12a, 13a of the elastic grasping members 11, 12, 13 close gradually to grasp the foreign body and the like.
Lengths of the respective elastic grasping members 11, 12, 13 are adjusted so that the circular pawl portions 11a, 12a, 13a of the elastic grasping members 11, 12, 13 constructing the elastic grasping section 14 are not brought into contact with one another. That is, the circular pawl portions 11a, 12a, 13a are arranged at different positions in the longitudinal direction of the insertion section so as to be converged side by side in line.
Incidentally, in FIG. 1B, the symbol 16 designates a leading end member constructing a leading end portion of the insertion section 15 and the symbol 17 does a grasping section dropout preventing pin for preventing the dropping-out of a coupling tube which is fixedly attached to the plurality of elastic grasping members, from the insertion section.
But, since the grasping forceps 10 for the endoscope illustrated in FIG. 1A has the elastic grasping section 14 composed of the three elastic grasping members 11, 12, 13, gaps between the adjacent elastic grasping members become wide. Therefore, it is apprehended that the operator happens to drop the once grasped living body tissue or foreign body through the gaps between the adjacent elastic grasping members within the body cavity.
Further, since flexing degrees of the respective elastic grasping members constructing the elastic grasping section 14 are set to large values, when the wire diameter of the elastic grasping member is made thin, the gaps between the adjacent elastic grasping members become wider. Therefore, practically it is impossible to decrease the wire diameter of the elastic grasping member, so that the flexing degree of the elastic grasping member becomes small. As a result, it is apprehended that the elastic grasping members tend to keep the straight postures to injure the living body tissue at the time of picking out the cellular tissue to be inspected.
While the elastic grasping members 11, 12, 13 constructing the elastic grasping section 14 are pulled into an internal bore of the cylindrical leading end member 16 of the insertion section 15 by pulling the operating wire of the grasping forceps 10 for the endoscope to the hand side as shown in FIG. 2, when the leading end grasping portion 13a disposed nearest to the insertion section leading end surface 15a is brought into contact with the elastic grasping member 11 having the leading end grasping portion 11a disposed remotest from the insertion section leading end surface 15a as indicated by A in FIG. 2, the elastic grasping member 11 is pushed outwards beyond the extension line (depicted by the alternate long and short dash line) of the outer peripheral surface of the insertion section 15.
When the grasping forceps for the endoscope is removed by the pulling from the endoscope under the condition that the elastic grasping member is pushed outwards beyond the extension line of the outer peripheral surface of the as shown in FIG. 2, it is apprehended that there appear the problems that the inner surface of the treating instrument passing channel of the endoscope is scratched, the elastic grasping portion is deformed, the operability of the grasping forceps becomes worse due to increase in push-pull forces by frictional resistance produced between the leading end grasping portion and the treating instrument passing channel or the grasping forceps for the endoscope is broken by forcibly pulling the grasping forceps for the endoscope from the treating instrument passing channel disregarding the increase in push-pull forces.
It is an object of the present invention to provide a grasping forceps for an endoscope which is provided with an elastic grasping section which is capable of reliably grasp living body tissue or a foreign body without injuring the living body tissue.
It is another object of the present invention to provide a grasping forceps for an endoscope in which elastic grasping members and/or leading end grasping portions seldom entangle with one another at the time of closing a spread elastic grasping section.
It is still another object of the present invention to provide a grasping forceps for an endoscope which doesn""t drop a once grasped small living body tissue or foreign body through gaps between adjacent elastic grasping members.
It is a further object of the present invention to provide a grasping forceps for an endoscope in which a leading end grasping section and/or leading end portions of elastic grasping members don""t project outwards beyond an outer peripheral surface of an insertion section.
In brief, a grasping forceps for an endoscope according to the present invention includes a flexible insertion section, an operating wire passing through the insertion section, connected at its hand side end to an operating section and adapted to be advanced and retreated in accordance with an operating of the operating section, and an elastic grasping section disposed at the leading end portion of the operating wire and composed of at least four elastic grasping members having different lengths and having a habit of flexing such that leading end grasping portions formed at their leading ends tend to spread outwards from the center axis of the insertion section, wherein at the time of spreading the elastic grasping section, the leading end grasping portions formed at the leading ends of the plurality of elastic grasping members of different lengths spread in a spiral arrangement. On one hand, when the elastic grasping section is accommodated, at least the leading end grasping portion to be disposed nearest to the insertion section leading end surface and the elastic grasping member having the leading end grasping portion to be disposed remotest from the insertion section leading end surface both which constitute the elastic grasping section are in an inclined positional relation.
The other features and advantages of the present invention will become apparent sufficiently to those skilled in the art as disclose is made in the following description thereof.